Here's the 4 part promotional prequel movie for Yakuza 1. A lot of it isn't canon anymore because of Yakuza 0 but it's still a great watch as it gives insight on Kiryu's days at the Sunshine orphanage.

Even so it isn't Canon anymore I really liked the Prequel together with the main Movie. Everybody says there are no good Videogame Movies but this one is pretty awesome. It has some issues but nothing critical. The Prequel is emotional, the main movie is funny combined with action. Perfect.